Dispersion Diagram Analysis of Arrays of Multishell Multimaterial Nanospheres

In this paper, the characteristics of electromagnetic waves supported by three dimensional (3-D) periodic arrays of multilayer multimaterial spheres are theoretically investigated. The spherical particles have the potential to offer electric and magnetic dipole modes, where their novel arrangements engineer the desired metamaterial performance. Multilayer spheres are designed for controlling both electric and magnetic Mie scattering resonances around the same spectrum. A full wave spherical modal formulation is applied to express the electromagnetic fields in terms of the electric and magnetic multipole modes. Imposing boundary conditions will determine the required equations for obtaining dispersion characteristics /2π-/2π. A metamaterial constructed from unit-cells of multilayer multimaterial sphere is created. It is demonstrated such compositions can exhibit negative-slope dispersion diagram metamaterial properties in frequency spectrums of interest, where both electric and magnetic Mie scattering resonances occur. Different coatings such as silver, gold, indium-tin-oxide (ITO), Al:ZnO, (AZO) and Ga:ZnO (GZO) are used and the operating range and the losses of the resulting metamaterials are compared. It is presented that by adding the third layer to the core-shell structure, due to increased degrees of freedom, the metamaterials operation range will be tunable to the desired frequency.